I've just been where you are now and I had to re-install (sorry) after someone in alt.os.linux.gentoo kindly helped me out.

What you need to do is ensure that the disk has a valid 'Sun Disk Label' -- my first install didn't and I had real problems booting as a result (hence the need to re-install).

Before setting up any partitions on your new disk, select 's' from the fdisk menu to give your disk this label. You will be prompted for various aspects of your drive's geometry. Go with the defaults *but* watch the drive-speed: fdisk selected 5400RPM for my 7200RPM IBM Deskstar, which I over-ruled and things are fine.

That act will (should) change the nature of the partition setup: prompts, number of partitions, and types will change, and things will be as you expected from the Sparc install documentation.

I've found the Gentoo documentation, on the whole, to be excellent! That said, the SPARC Install guide doesn't do enough to make this partitioning quirk clear. To be fair though, it's probably as obvious to any Sparc bod how to partition drives (as it is to any PC bod like me). But now that second-hand Sparc gear is easier for us x86 guys to get hold of, there are still some differences in how things are done that need making clearer.

A small gripe. Mind you: Gentoo has still been the easiest and most rewarding Linux for me to set-up and maintain (I've used Mandrake, Red Hat and still use SuSE).

You've got a non-Sun disclabel. Hit 's' to change. The docs do say that somewhere I think...

Perhaps I was mistaken, but that's what I thought I was attempting to do.

To fully quote what I quoted earlier from the docs:

"Now that the in-memory partition table is empty, we're ready to create the Sun Disk Label partition. To do this, type n to create a new partition, then type 3 to create the partition. When prompted for the first cylinder, hit enter. When prompted for the last cylinder, hit enter. After you've done this, type t to set the partition type, and then type in 5 to set the partition type to "Whole disk".

Yes, I went back and scratched my head over that one too. What it says in the instruction doesn't map to the choices available to you. Completely confusing!

Trust me. Clear your partitions, select 's', '0' (zero) and respond to the questions about disk-geometry; then set up your boot and swap partitions and when you get to the 3rd partition (the sun disk label) you'll be on reassuringly familiar turf ready to set up your 4th (root) partition.

In fdisk use the "s" command to create a new empty sun disklabel.
(If that works for you fine => head, sector ... guessing or knowing)
P.S.: Check if you have all space availabe on the disk by creating a new partition and using all the space. (+19G if you have a 20G hdd)

There is the other solution get userself a solaris8 or 9 and use solaris to auto partition your disk,